neazoi
Advanced Member level 6
In my page I have designed this franklin oscillator **broken link removed**
Now I want to investigate it's conversion to a regenerative receiver.
As far as I can understand, I need to limit the feedback or the amps gain in the oscillator section, so that oscillation stops at some point. This will be the edge point of regeneration.
By using a variable voltage to the oscillator this might happen but there will be quite a lot of frequency pull I bet. So I am thinking of the capacitor method.
1. How about replacing the 470pF capacitor with a variable one, do you think that will work without considerable frequency pulling?
Alternatively I could replace one of the 3.3pF with a variable one but I do not think it is a good idea to mess with the resonator-depended components.
2. If I couple the antenna (through an RF preamp for isolation) to the coil, then will demodulated audio present to the top of the 470pF? (collector of the second BJT)
Because there is a big C-B resistor there, the BJT may act as a detector. I may need to change this to 1M or so...
What do you think of these 2 points above?
Now I want to investigate it's conversion to a regenerative receiver.
As far as I can understand, I need to limit the feedback or the amps gain in the oscillator section, so that oscillation stops at some point. This will be the edge point of regeneration.
By using a variable voltage to the oscillator this might happen but there will be quite a lot of frequency pull I bet. So I am thinking of the capacitor method.
1. How about replacing the 470pF capacitor with a variable one, do you think that will work without considerable frequency pulling?
Alternatively I could replace one of the 3.3pF with a variable one but I do not think it is a good idea to mess with the resonator-depended components.
2. If I couple the antenna (through an RF preamp for isolation) to the coil, then will demodulated audio present to the top of the 470pF? (collector of the second BJT)
Because there is a big C-B resistor there, the BJT may act as a detector. I may need to change this to 1M or so...
What do you think of these 2 points above?